There has been known a process for assaying an endotoxin contained in a vital sample with the use of a component of limulus amebocyte lysate [limulus test (LAL-Test)]. For example, U.S. Pat. No. 4,495,294 corresponding to JP-B-63-55671 discloses an assay method wherein a vital sample containing protein cell granules (for example, plasma, serum, albumin, globulin, ascites, articular fluid or external or internal exudation or excretion such as urine), which has been treated with an acid having a pKa of 3 or less at 25.degree. C. at pH 3 or below, is assayed with the use of the limulus amebocyte lysate component (the term "JP-B" as used herein means an "examined Japanese patent publication").
However, it is found that the detection ratio of an endotoxin in whole blood assayed by the method described in the aforesaid patent is not as high as expected (i.e., 50 to 60%).
Under these circumstances, the present invention aims at providing a process for efficiently assaying an endotoxin in whole blood at an extremely high detection ratio.
On the other hand, there has been known that it is very difficult to accurately assay an endotoxin in a protein solution.
The present invention further aims at providing a process for accurately assaying an endotoxin contained in a solution of, for example, protein, protease or protease inhibitor.